DE4415524B4 - Valve control system for an internal combustion engine - Google Patents

Abstract

Valve control system for one Internal combustion engine, which is electromechanically actuated and comprising the following components: a crankshaft, at least one camshaft (126), which experiences torque fluctuations on rotation, a mounted on the camshaft rotor (160) with two spaced Wings (160a, 160b), one opposite the camshaft limits rotatable, seated on the camshaft casing (132) with two spaced chambers (132a, 132b) in which the wing (160a, 160b), a drive between crankshaft and camshaft, and a control device having a valve for Adjusting the rotational position of the housing, dependent of torque fluctuations of the crankshaft, the valve as Slider valve (192) is formed, the slide (200) two Bunde (200a, 200b), from the slide the connection of return lines (194, 196) from one chamber (132a, 132b), depending on the slide position is controlled, an inlet line (182) via which the valve with each Chamber (132 a, 132 b) is connected, check valves in the inlet line (184, 186) are provided, with which the flow from each chamber ...

Description

The The invention relates to a valve control system for an internal combustion engine the preamble of the claims 1 and 13.

An electromechanically actuated valve control system of this type is known from US 5,184,578 known. In this valve control system, the slider of the spool valve is supplied with hydraulic oil at both ends to balance the forces acting on the spool. As a result, pressure changes or viscosity fluctuations can be eliminated and maintain a central position of the slide.

adversely However, the position of the slider is in the warm-up phase the engine is not cleanly controlled. When starting it takes several seconds, until the full oil pressure established. While At this time the position of the slide is unknown. Furthermore, that is dynamic response slow. Even if the engine speed reaches a normal operating speed, There are different operating characteristics depending on the engine. So owns a new engine at high speed and low temperature another oil pressure as an older one Engine in the hot Condition and idle. Do you want these different operating characteristics capture (e.g., by enlarging the Cross sections of the slide and smaller springs), this leads to this to a sluggish response and a design of the higher gain regulator to maintain stability. Such regulators with higher gain However, make the valve control system sensitive to manufacturing tolerances and fluctuations in operating behavior. This leads (for example in the Pulse width control for zero setting of the slide valve) to a deterioration of the control behavior in the overall system.

Further to lead the moving parts of a pulse-controlled solenoid valve, as usual used in such systems, to annoying noises. In operation switches the solenoid valve at each drive pulse the full stroke. The fast Switching leads to flutter the armature and the plunger, i. a hammering with high frequency that the sounds causes.

Of the Invention is based on the object, a valve control system of in the preamble of the claims 1 and 13 specified type so that a balance the forces acting on the slider of the slide valve also at unfavorable Operating conditions of the internal combustion engine is possible in a simple manner.

These The object is achieved by the valve control system defined in claims 1 and 13 solved.

According to the invention, the slide of the slide valve is vented through a ventilation channel leading to the atmosphere, so that it is relieved of fluid pressure. According to the invention thus eliminating the loading of one end of the slide with hydraulic fluid from the engine lubricating oil system at full hydraulic pressure, as is the case with previously known valve control systems. The force at the other end of the vented spool is due to an electromechanical actuation, preferably a variable force solenoid, acting directly on the spool when driven by an electrical signal provided by an operation control unit (ECU) in accordance with various engine parameters , The operation control unit receives signals from sensors for the positions of the camshaft and crankshaft and uses this information to calculate a relative phase angle. The preferred embodiment uses a closed control system, as for example in the US 5,184,578 is explained to correct a phase angle error. The invention thus provides an economical solution to the above problems and has even more advantages.

is The relationship between the position of the slider and the control signal (solenoid current) independently from engine oil pressure, so all account for the oil pressure and its fluctuations related problems. For example, this leads too low operating oil pressure when starting the engine not to errors, as the signal of the operating control unit immediately activates the electromagnet, which positions the slide directly.

Of the Electromagnet with adjustable force (proportional solenoid) also triggers the problem of sluggish dynamic control behavior. The electromagnet can be so fast like the mechanical response of the gate valve and with Safety much faster than the previously known "fully hydraulic" spool valves. The higher one Speed allows higher gains in the control loop and reduces the system sensitivity to component tolerances and operating conditions.

Further the stroke of the proportional solenoid is very small and is powered by electricity the operating control unit controlled, in contrast to the complete switching strokes a Pulse width controlled electromagnet. Because the required stroke rarely reaches the end positions, the hammering and flutter is avoided and the system works virtually noiselessly.

Probably the most important advantage over previously known valve control systems is the improved control of the base system. The invention provides a device with significantly improved characteristics to quickly detect and accurately follow an input signal for phase adjustment.

There the inventively designed Valve control system not from oil pressure dependent is, it can also be used where an operation without pressure oil desirable is, for example, in engines with a belt drive for the valve control.

Further advantageous embodiments of the invention are defined in the dependent claims.

embodiments The invention are explained below with reference to the drawing. It demonstrate:

1 a partial view of a valve train with double camshaft and a valve control system;

2 a partial view of the intake camshaft in advance position relative to the exhaust camshaft;

3 a partial view along the line 3-3 in 6 with omitted parts in the retard position;

4 a partial view similar 3 with the intake camshaft in advance position opposite to the exhaust camshaft;

5 a partial view of the back of components in 1 ;

6 a partial view along the line 6-6 in 4 ;

7 a partial view along the line 7-7 in 1 ;

8th a section along the line 8-8 in 1 ;

9 a section along the line 9-9 in 1 ;

10 an end view of a camshaft with a modified version of the valve control system;

11 a view similar 10 with omitted parts;

12 a section along the line 12-12 in 10 ;

13 a section along the line 13-13 in 10 ;

14 a section along the line 14-14 in 11 ;

15 an end view of an element of the valve control system of 10 to 14 ;

16 an end view of an element of 15 from the other end;

17 an end view of the element of 15 and 16 ;

18 an end view of the element of 17 from the other end;

19 a simplified schematic representation of the valve control system of 10 to 18 ; and

20 a simplified schematic representation similar 19 in a modified version.

In the embodiment of the 1 to 9 is a sprocket 24 on a crankshaft 22 wedged, whose rotation on a camshaft 26 for actuating the exhaust valves of the engine via a chain 28 is transferred to the sprocket 24 and one on the camshaft 26 attached sprocket 30 is looped. Chain tensioners can be used, even if they are not shown. The sprocket 30 is twice the size of the sprocket 24 , This has a rotation of the camshaft 26 The result is half the size of the crankshaft 22 So right for a four-stroke engine. Instead of the chain 28 can also be provided a belt.

The camshaft 26 owns another sprocket 32 ( 3 . 4 and 6 ), which is rotatable by a certain circumferential angle relative to the camshaft, but otherwise with the camshaft 26 rotates. The rotation of the camshaft 26 is about a chain 36 by means of the sprocket 32 and the sprocket 38 on a camshaft 34 transferred for the intake valves. The sprockets 32 and 38 have the same diameter, so that there are corresponding speeds. Instead of the chain 36 can also be provided a belt.

6 shows that each one end of the camshafts 26 . 34 in camps 42 and 44 of the cylinder head 50 is stored, which is shown only in parts and bolted to the engine block, namely with screws 48 , The other not shown ends of the camshafts 26 and 34 are similarly mounted on the cylinder head. The sprocket 38 sits on the camshaft 34 outside the cylinder head 50 , Also the sprockets 30 and 32 lie side by side outside the cylinder head 50 , where the sprocket 32 opposite the sprocket 38 lies and the sprocket 30 just outside the sprocket 32 according to the position of the sprocket 24 is arranged.

The sprocket 32 has a bow-shaped carrier 52 (S. 7 and 8th ) formed on it and extending from the sprocket 32 through an arcuate opening 30a in the sprocket 30 extends to the outside. On the sprocket 30 is a curved housing 46 screwed, in which various hydraulic components of the control system are arranged; it carries pivotally the housing-side end of two oppositely working, single-acting hydraulic cylinder 54 and 56 located on opposite sides of the longitudinal axis of the camshaft 26 lie. The piston-side ends of the cylinders 54 and 56 are pivotable on an arcuate bracket 58 hinged, in turn, on the sprocket 32 with several screws 60 is attached. So if one of the cylinders 54 . 56 expands and simultaneously pushes the other, so the circumferential position of the sprocket changes 32 opposite the sprocket 30 , either leading the sprocket 32 if the cylinder 34 as it is in the 2 and 4 is shown, or trailing when the cylinder 56 shoves out, as in the 1 . 3 . 7 and 8th is shown. In any case, takes place when advancing or lagging the sprocket 32 opposite the sprocket 30 which optionally in response to the torque direction in the camshaft 26 allowed or avoided, leading or lagging the position of the camshaft 34 opposite to the camshaft 26 due to the chain connection between the sprocket 32 that on the camshaft 26 limited rotatably mounted, and the sprocket 38 which is on the camshaft 34 is attached. This relationship can be seen in the drawing, given the relative position of a timestamp 30b on the sprocket 30 and a timestamp 38a on the sprocket 38 in the retard position of the camshaft 34 considered, s. 1 and 3 , and their relative positions in the advanced position of the camshaft 34 , s. 2 and 4 ,

The 10 to 20 show two embodiments of the invention, in which a housing in the form of a sprocket 132 rotatable on a camshaft 126 is stored. The camshaft 126 can be considered as the only camshaft of an internal combustion engine with a camshaft, either as an OH camshaft or as a block.

Furthermore, the camshaft 126 operate either the intake valves or the exhaust valves of a double camshaft engine. Anyway, that's the sprocket 132 and the camshaft 126 rotatable against each other, and the rotation is done by a torque acting on the sprocket 132 from an endless roller chain 138 is exercised, which is partially shown and the unillustrated crankshaft and the sprocket 132 is looped. As will be explained in more detail below, the sprocket is 132 on the camshaft 126 rotatably mounted so that it is at least a limited circular arc relative to the camshaft 136 during the rotation of the camshaft can pivot, which is the phase angle of the camshaft 126 adjusts to the crankshaft.

An annular rotor 160 sits firmly on the camshaft 126 and has two diametrically opposed radially outwardly projecting wings 160a . 160b and is at an enlarged end part 126a the camshaft 126 with screws 162 attached by the rotor 160 in the end part 126a to grab. Here is the camshaft 126 further with a stop shoulder 126b provided so that the camshaft is accurately positioned relative to an engine block, not shown. The rotor 160 is also relative to the end part 126a with the help of a dowel pin 164 accurately positioned. The wings 160a . 160b sit in radially outward facing chambers 132a . 132b of the sprocket 132 , wherein the circumferential length of the chambers 132a . 132b is slightly larger than the circumferential length of the wings 160a . 160b , which sit in each chamber and thus a rotational movement of the sprocket 132 opposite the rotor 160 allow. The chambers 132a . 132b close around the wings 160a . 160b over spaced, transverse annular plates 166 . 168 attached to the rotor 160 and thus with respect to the camshaft 126 with screws 170 are fixed, which extend through the assembly. Further, the inner diameter 132c of the sprocket 132 opposite the outer diameter of the part 160d of the rotor 160 between the wings 160a . 160b sealed, and the tips of the wings 160a . 160b of the rotor 160 are with slots 160e . 160f provided for receiving seals. This is the chambers 132a . 132b of the sprocket 132 Completed hydraulically pressure-tight, and this also applies to each chamber 132a . 132b as well as the section on each side of the wings 160a . 160b ,

The operation of the embodiment according to the 10 to 18 is with the help of 19 and 20 understandable. Needless to say, the hydraulic control system is the 19 and 20 Also, in a valve control system with opposing hydraulic cylinders according to the embodiment of 1 to 9 can be used, as well as for the valve control system with wings according to 10 to 18 ,

In any case, hydraulic fluid, here in the form of engine lubricating oil, flows into the chambers 132a . 132b via a common inlet pipe 182 , This ends in the middle between two backs shock valves 184 and 186 attached to the chambers 132a . 132b over branch lines 188 . 190 are connected. The check valves 184 . 186 have annular seats 184a . 186a , so that pressure medium through the check valves 184 . 186 can flow into the chambers. The flow is interrupted by valve balls 184b . 186b that of feathers 184c . 186c are charged. Thus, the chambers can be initially filled via the check valves and fluid can be replenished to compensate for leakage. The oil gets into the inlet pipe 182 via a slide valve 192 which is in the camshaft 126 sits, and returns from the chambers via return lines 194 . 196 to the slide valve 192 back.

The slide valve 192 consists of a cylindrical housing 198 and a ventilated slide 200 that in the cavity 198a slides. The slider 200 has cylindrical coils 200a . 200b at one end, each collar via its control edge, the return flow from the lines 194 . 196 controls, wherein in the middle position, namely the zero position of the slider 200 , both return lines 194 . 196 are closed off, like the 19 and 20 demonstrate.

The position of the slider 200 in the case 198 is from a spring 202 that affects the end of the covenant 200a acts. This presses the spring 202 the piston 200 to the left. The inlet pipe 182 receives pressure medium oil (engine oil) directly from the main oil distribution 230 of the engine via a line 230a , on the slide 200 past. This oil also lubricates the bearing 232 for the camshaft 126 ,

The regulation of the slide position is directly dependent on an electromechanical actuator 201 , preferably a proportional magnet, in 19 is shown. The magnet receives power via a cable 238 that through the case 201d to the winding 201 that is the anchor 201b advances. The anchor 201b press on the extension 200c of the slider 200 and pushes the ventilated slide 200 to the right, like 19 shows. When the force of the spring 202 with the anchor 201b in the opposite sense, the slide remains 200 centered in its zero position. That's how the slider works 200 in each direction by increasing or decreasing the magnetic flux. Of course, the design of the magnet 201 Also be reversed so that the force on the slide extension 200c do not push, but pull. This means a modification of the spring 202 , which in turn must counteract the armature movement. However, there are cases where the slider 200 to go to the left in the preloaded position. The arrangement of the spring 202 in the cavity 198c or in 198a like this in 19 respectively. 20 shown, make sure the slider 200 returns to the preloaded position when on the magnet winding 201 no current signal is applied, for example, when the energy fails or the engine is stopped.

The displacement of the anchor 201b depends on the current in the winding 201 , which is a control signal from a motor controller 208 (ECU) is supplied as in 19 is shown schematically. In known designs of the valve control system, it must be on the slide extension 200c applied force with the force of the spring 202 plus the oil pressure in the chamber 198a be balanced, the end of the covenant 200a applied when the zero position of the slider 200 it is asked for. The problem with this compensation is that the oil pressure can fluctuate very much. So the optimal solution is to make the control system independent of the fluctuating oil pressure.

According to the invention, the pressure in the chamber 198a relieved, so only needs the power of the anchor 201b against the force of the spring 202 to be balanced to the zero position of the slider 200 to reach. The pressure relief in the room 198a can be done, for example, by providing a flow path in the bypass to the slide 200 that is, no inner channel for supplying oil to the inlet pipe 182 used, as was the case so far. The bypass for the slide 200 can be a connecting bypass line 220a directly to the inlet line 182 be, with an exchange of the inlet check valve 222a against the check valve, which has previously been placed in the inner channel of the slide. In conjunction with the alternative flow path, aerating the slide completes 200 to the atmosphere via the ventilation duct 198d the intention of the pressure in the room 198a to relieve, so far the end face of the covenant 200a has acted upon.

Thus, if the influence of the oil pressure is eliminated, so are the position of the slide 200 only responsible for more forces that are predictable. The power of the anchor 201b corresponds to the current signal in the winding 201 , and the power of the spring 202 is also determinable (depending on the spring position). This is the position of the slider 200 solely dependent on the current signal.

The magnet used in the preferred embodiment has a cylindrical armature accordingly 19 , The air gap 201c extends circumferentially around the anchor 201b and can not have magnetic bearing material. Shifts the anchor 201c axially, so increases the cylindrical portion of the gap 201c but the force and the distance from the winding remain constant. Since the force of the axial anchor position is relatively unaffected, it is not necessary that the Ab stood between housing 201d and slider 200 is chosen exactly.

Another embodiment of the invention is in 20 shown. There, a proportional magnet with a flat armature or variable air gap is used. The force is the square of the air gap 201c inversely proportional. So it is advantageous, the air gap 201c to limit to a relatively small value. If you use a lifting amplifier in conjunction with the magnet with variable gap, so you can achieve a gain in power. The anchor 201b is with the slider extension 200c via a lever arrangement 201e connected, which provides the power amplification. You can so the size of the actuator 201 reduce, so that also the current signal in the winding 201 gets smaller, but the valve lift remains the same.

After the movement of the slider in each direction only the imbalance between an electrically generated force at a slider end 200a and the spring force on the other end 200b is responsible (as opposed to acting on both ends hydraulic forces from a common source), the valve control systems are the 19 and 20 completely independent of the hydraulic system pressure. This eliminates all the measures that were required for a wide range of changing oil pressures and resulting from certain characteristics of individual engines. According to the invention it is thus possible, the slider 200 to adjust quickly and accurately in its zero position.

The rotor 160 can alternately clockwise and counterclockwise from the torque fluctuations in the camshaft 126 can be influenced, and these fluctuations can cause the rotor to oscillate 160 and thus the camshaft 126 opposite the sprocket 132 to lead. In the in the 19 and 20 However, shown slide position, these rotational fluctuations of the pressure medium in the chambers 132a . 132b on both sides of the wings 160a . 160b avoided, because the oil from any of the chambers 132a . 132b flows. Both return lines 194 . 196 are from the slider 200 shut off. But should the camshaft 126 and the rotor 160 counterclockwise with respect to the sprocket 132 be twisted, so it is only necessary, the current signal in the winding 201 to enlarge. This pushes the anchor 201b to the right and thus also the slider 200 so that the return line 194 opens. In this state pump torque fluctuations in the camshaft 126 Oil from the chamber 132a , and thus the wing can 160a in the direction of the chamber 132a Turn off, was drained from the oil. A reversal of the rotor 160 Does not occur because the torque fluctuations in the camshaft 126 be directed opposite each other, though and until the slider 200 Runs to the left as the flow through the return line 196 from the federal government 200b of the slider 200 is locked. While the 19 and 20 show a closed passage, has the circumference of the rotor 160 an open passage slot 160c , as the 10 . 11 . 15 . 16 and 17 show through the oil from the chamber 132a on the right side of the grand piano 160a in the chamber 132b on the right side of the grand piano 160b can pass, which are the non-active sides of the wings 160a . 160b are. This is a counterclockwise movement of the rotor 160 opposite the sprocket 132 when flow over the return line 164 takes place, and a clockwise movement when the flow over the return line 196 he follows.

Further, the inlet pipe 182 over an extension 182a to the non-active side of each wing 160a respectively. 160b connected; here is the wing 160b ge shows, so that constantly oil on the non-active sides of the wings 160a . 160b can flow for a better Drehausgleich, whereby the damping of the rotor movement is improved and a better lubrication of the bearing surfaces of the rotor 160 is achieved. This post-flow of oil does not affect the operation of the electromagnetic actuator 201 , The Nachströmöl is continuous for the wings 160a and 160b intended.

Claims (13)

Valve control system for an internal combustion engine, which is actuated electromechanically and has the following components: a crankshaft, at least one camshaft ( 126 ), which undergoes torque fluctuations upon rotation, a rotor mounted on the camshaft ( 160 ) with two spaced wings ( 160a . 160b ), a relative to the camshaft limited rotatable, seated on the camshaft housing ( 132 ) with two spaced chambers ( 132a . 132b ), in which the wings ( 160a . 160b ), a drive between crankshaft and camshaft, and a control device with a valve for adjusting the rotational position of the housing, depending on torque fluctuations of the crankshaft, wherein the valve as a slide valve ( 192 ) is formed, whose slide ( 200 ) two bundles ( 200a . 200b ), from the slide the connection of return lines ( 194 . 196 ) from one chamber each ( 132a . 132b ) is controlled according to the slide position, an inlet line ( 182 ) via which the valve with each chamber ( 132a . 132b ), in the inlet line check valves ( 184 . 186 ) are provided, with which the flow from each chamber is shut off in the direction of slide valve, and sensors ( 207a . 207b ) are provided for detecting the positions of the crankshaft and camshaft, wherein a motor controller ( 208 ) a relative phase angle between crankshaft and camshaft is calculated, the slide ( 200 ) depending on a signal supplied by the engine control from an electromechanical actuator ( 201 ) is adjustable, and the slider ( 200 ) by a biasing means ( 202 ) is biased so that the slider is pushed to the full advance position when the actuator is turned off, characterized in that the slide ( 200 ) through a ventilation channel leading to the atmosphere ( 198d ) is vented so that it is relieved of fluid pressure. Valve control system according to claim 1, characterized in that the two wings ( 160a . 160b ) one chamber each ( 132a . 132b ) into a first and second part and both parts of each chamber are pressure-sealed. Valve control system according to claim 1 or 2, characterized in that the control device is reversible, so that fluid from the first and second sections in each chamber ( 132a . 132b ) and can cross into the other first and second sections of each of the two chambers. Valve control system according to one of claims 1 to 3, characterized in that the engine lubricating oil is used as a fluid and a connecting line ( 230a ) to a pressure oil pump ( 230 ) of the control device is provided. Valve control system according to one of claims 1 to 4, characterized in that opposing portions of the first and second chambers ( 132a . 132b ) via one line ( 160c . 182a . 188 . 190 ) to the inlet line ( 182 ) are connected for pressure medium. Valve control system according to claim 5, characterized in that the inlet line ( 182 ) to a bypass line ( 220a ) connected to the ventilated slide ( 200 ) and in which a check valve ( 222a ) is provided, the flow from the inlet line ( 182 ) through the valve housing ( 198 ) stops. Valve control system according to one of claims 1 to 6, characterized in that the electromechanical actuating device ( 201 ) is an electromagnet with adjustable force. Valve control system according to claim 7, characterized in that for the electromagnet a winding ( 201 ), an anchor ( 201b ) within the winding, an air gap ( 201c ) and a housing ( 201d ) is provided, is actuated by a current signal in the winding of the armature to the slider ( 200 ) to exercise a force. Valve control system according to claim 7 or 8, characterized in that between the actuating device ( 201 ) and the slide valve ( 192 ) A Hubverstärkung is provided, with which the valve lift is extended. Valve control system according to claim 9, characterized in that the lifting amplifier is a lever arrangement ( 201e ). Valve control system according to one of claims 7 to 10, characterized in that the actuating device ( 201 ) opposite end face of the slider ( 200 ) of a spring ( 202 ) is pressurized and ventilated ( 198d ). Valve control system according to one of claims 1 to 11, characterized in that the slide valve ( 192 ) in a bore of the seated on the camshaft housing ( 132 ) is installed. Valve control system for an internal combustion engine, which is electromechanically actuated and has the following components: a crankshaft ( 22 ), at least one camshaft ( 26 ), which undergoes torque fluctuations upon rotation, a device mounted on the camshaft with counter-actuated hydraulic piston-cylinder assemblies for changing the angular position between two on the camshaft ( 26 ) seated sprockets ( 30 . 32 ) and with a valve for controlling the piston-cylinder arrangements with pressure medium, wherein the valve as a slide valve ( 192 ) is formed, whose slide ( 200 ) two bundles ( 200a . 200b ), from the slide the connection of return lines ( 194 . 196 ) is controlled from one Zyliderraum depending on the slide position, an inlet line ( 182 ) via which the valve is connected to each cylinder chamber, in the inlet line check valves ( 184 . 186 ) are provided, with which the flow is shut off from each cylinder space in the direction of the slide valve, sensors ( 207a . 207b ) are provided for detecting the positions of the crankshaft and camshaft, wherein a motor controller ( 208 ) a relative phase angle between crankshaft and camshaft is calculated and the slide ( 200 ) of the spool valve depending on one of the engine control ( 208 ) supplied by an electromechanical actuator ( 201 ) is adjustable, and the slider by a biasing means ( 202 ) is biased so that the slider is pushed to the full advance position when the actuator is turned off, characterized in that the slide ( 200 ) through a ventilation channel leading to the atmosphere ( 198d ) is ventilated, so he fluid pressure is relieved.